/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package org.apache.iotdb.db.conf.directories.strategy;

import org.apache.iotdb.commons.utils.JVMCommonUtils;
import org.apache.iotdb.db.exception.DiskSpaceInsufficientException;

import java.util.List;

public class SequenceStrategy extends DirectoryStrategy {

    private int currentIndex;

    @Override
    public void setFolders(List<String> folders) throws DiskSpaceInsufficientException {
        super.setFolders(folders);

        // super.setFolders() ensures at least one folder is not full,
        // so currentIndex will not be -1 after loop
        currentIndex = -1;
        for (int i = 0; i < folders.size(); i++) {
            if (JVMCommonUtils.hasSpace(folders.get(i))) {
                currentIndex = i;
                break;
            }
        }
    }

    @Override
    public int nextFolderIndex() throws DiskSpaceInsufficientException {
        int index = currentIndex;
        currentIndex = tryGetNextIndex(index);

        return index;
    }

    private int tryGetNextIndex(int start) throws DiskSpaceInsufficientException {
        int index = (start + 1) % folders.size();
        while (!JVMCommonUtils.hasSpace(folders.get(index))) {
            index = (index + 1) % folders.size();
            if (index == start) {
                throw new DiskSpaceInsufficientException(folders);
            }
        }
        return index;
    }
}
